Mechanisms of Nanomaterials-based Combination Adjuvants

PROJECT SUMMARY The discovery of pattern recognition receptors (PRRs), including toll-like receptors (TLRs) and NOD-like receptors (NLRs) has led to the investigation of molecular agonists of innate immunity in adjuvant formulations. An emerging paradigm is that careful selection of adjuvant combinations can result in complementary and even synergistic enhancement of vaccine-induced immune responses. Most combination adjuvants under investigation are chemically heterogeneous mixtures of depot adjuvants mixed with PRR agonists and suffer from batch-to-batch variability and poor chemical definition making investigation of mechanisms and safety a challenge. Our lab investigates self-assembling peptide nanofibers (PNFs) as vaccine adjuvants. A key advantage of PNFs over emulsion adjuvants is that the primary sequence of the self-associating peptide can be designed to control the physicochemical features of PNFs such as morphology, charge, chirality, or hydrophobicity, which are key contributors to adjuvant activity. Mechanistic insights into the mode of action indicates that unlike PAMPs, PNFs do not cause DC maturation but facilitate the release of DAMPs related to osmotic/oxidative stress. In this application, we propose to develop combination adjuvants composed of chemically defined DAMP-inducing peptide nanofibers (PNFs) and TLR2/NOD2 agonists. Our objectives are to understand how molecular mechanisms of DAMP-inducing PNFs and PRR agonists orchestrate innate immune signaling and induce responses that are complimentary, synergistic, or inhibitory for balancing immunogenicity with safety. In aim 1, we will examine the effect of PNFs with varying physicochemical properties and TLR2 or NOD2 agonist combinations on DC activation, DAMP release, and antigen presentation. In aim 2, using a design of experiments (DOE) approach, we will develop an optimal formulation with precisely controlled PNF-TLR2 and PNF-NOD2 combinations and determine the molecular mechanisms of innate immunity in DCs using various KO mouse models. In aim 3, we will validate the efficacy of PNF-TLR2-NOD2 combination adjuvants and investigate translational potential using human DCs. Outcomes of the proposed studies will advance our understanding of the molecular mechanisms that mediate innate immune responses to PNF-PRR agonist adjuvant combinations and will lead to new combinatorial- adjuvant platforms for combating infectious and non-infectious diseases with high translational potential.